A known micro-fabrication technique includes a photolithographic technique including subjecting a negative-type photosensitive resin to exposure to light and development to form a patterned structure. This technique is widely used in applications such as semiconductor integrated circuit production applications, semiconductor exposure mask production applications, and applications of the production of various microelectromechanical systems (MEMS). In an example of the MEMS production application, the technique is used for the production of liquid discharge head nozzles. Steppers with i-line light sources are widely used as exposure devices. In the field of this technique, the production of more complicated and sophisticatedly-shaped structures has recently been demanded, and therefore, a negative-type photosensitive resin exhibiting high photosensitivity to light from a light source and high shaping accuracy has been demanded.
Japanese Patent Application Laid-Open No. 2008-256980 discusses a photosensitive resin composition which contains a polyfunctional epoxy resin and a cationic polymerization initiator as an example of such a negative-type photosensitive resin.
U.S. Pat. No. 6,155,673 discusses an example of the structure of a liquid discharge device having nozzles in which bubbles produced by heating a heat resistor are allowed to communicate with outside air so that ink droplets can be discharged.
However, the above composition does not have satisfactory properties in some cases for the reason below. For example, when a complicated structure such as a tapered discharge port for a liquid discharge device is formed using such a negative-type photosensitive resin composition and an i-line light source, an undesired shape such as a partially-rounded edge may be formed.